telemetry: invert dependency on metrics library

telemetry: invert dependency on metrics library

Rather than having the telemetry library depend on the metrics
lib we invert the dependency so that metrics instead depends
on telemetry lib, and registers the needed functions with it
at init time. This prepares the way for a cleaner telemetry
architecture to be applied in later patches.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Keith Wiles <keith.wiles@intel.com>